The present invention is directed to a method and to a device for drawing in a web in a web-fed rotary printing press. The web has a draw-in tip which is made thicker than the rest of the web.
A device for attaching a web of material to a carrier of a web draw-in device is known from EP 0 118 860 B1. A fastening device, that receives the end of the web of material, is loosely suspended by a loop fastened on the former from the carrier, of a draw-in element.
A draw-in device is described in G 92 15 764 U1, in which a cable, which is attached to the draw-in tip, is pushed vertically in respect to the conveying direction into the openings of carriers. The cable is maintained on the carrier, secure against slipping out opposite the conveyance direction, by the use of a headpiece of the cable.
DE 198 37 361 A1 discloses a device for drawing in a web of material to be imprinted. A free end of the draw-in tip is threaded through an opening of a carrier which is connected with the draw-in device and is made into a loop by a hook-and-loop closure.
EP0 425 741 A1 shows a device for drawing in a web and having a draw-in assembly. A positive connection opposite and transversely to the conveying direction with a carrier arranged on the draw-in assembly can be made by the use of a coupling element arranged on a draw-in tip. The coupling element, embodied in a stepped manner, and the carrier can be connected with each other, or released from each other, by a relative movement along the conveying direction.
The object of the present invention is based on providing a method and a device for drawing in a web.
In accordance with the present invention, this object is attained by providing the web to be drawn in with a thickened portion. This thickened portion is received in a carrier that is part of the web draw-in device. The thickened portion is slid into the carrier in a direction perpendicular to the web conveying direction and is then moved in the carrier in a direction parallel to the conveying direction. This second movement takes place with limited travel in the direction perpendicular to the conveying direction.
The advantages which can be realized by the present invention reside, in particular, in that the connection between the draw-in assembly or device and the draw-in tip is positive in the conveying direction, which connection is embodied in a self-securing manner in respect to releasing the connection during the operation, i.e. when drawing the web in. The danger of a spontaneous and unintentional release of the connection, such as can occur in a connection with simply designed carriers, is reduced by a travel limitation imposed on the draw-in tip on all sides of the tip, which is closed to a great extent.
The connection between the draw-in tip and the draw-in assembly or device is substantially achieved in an advantageous manner by the requirement of a two-step movement, which movement is guided to a great extent, of the draw-in tip in respect to the carrier. In an advantageous manner, the suspension and securing of the tip in the carrier takes place in two defined movement directions, which extend almost perpendicularly with respect to each other. In a first step, the suspension of the tip in the carrier takes place in a direction which is almost perpendicular in respect to the web conveying direction. In a second step, the connection is secured by a relative movement between the clamping element and the draw-in tip in which the tip moves relative to the clamping element in a direction opposite to the web conveying direction. The movement, which is guided to a great extent and which extends almost perpendicularly in respect to the conveying direction for a suspension in a narrowly bordered forward direction provides increased assurance against unintentional release of the tip from the carrier.
In a particularly advantageous embodiment, a sequence of two defined movements is required for connecting, or releasing the tip and the carrier, wherein one movement represents a rotational movement, which movement is not one typically occurring in the draw-in process, in a direction R. With this sequence of movements, the connection is not sensitive to unintentional release because of fluctuations in the web tension or in web speed during draw-in.
In at least one area in which the draw-in tip, or a thickening at the draw-in tip, and the carrier engage each other, a first movement is possible only guided along in a direction which is predetermined to a great extent.
In addition to providing a high degree of assurance that the connection will not become undone, a substantial advantage of the present invention is its rapid and simple operability. Elaborate opening or closing by the use of tools, gluing or threading into closed eyes is not required.